The present invention relates generally to processing systems and specifically to a power supply system for a processing system that provides an auxiliary output voltage.
Typically a power supply in a desktop computer requires the maintenance of an auxiliary output voltage for the operation of the service processor and for internal house keeping. This auxiliary output voltage is generally a separate small power supply within a main power supply and is used to provide continuous current even when other power outputs are turned off. However, this small power supply adds extra cost and instrumentation to the overall system.
FIG. 1 depicts a conventional power supply system. The area enclosed by the dashed line contains a flyback auxiliary power supply 10 of the power supply system. The remaining portion represents the main power supply 11. The main power supply 11 includes a first capacitor 26 coupled to a transformer 22. The supply 11 also includes a transistor 36 coupled to the transformer 22, diodes 20, 28, 30, an inductor 32 coupled to diode 28, and a second capacitor 34 coupled to the inductor 32. The flyback auxiliary power supply 10 includes a transformer 12. The transistor 14 is coupled to the transformer 12 and a pulse width modulator 15. The transformer 12 is coupled to a diode 16. The diode 16 is coupled to a capacitor 18.
Because the flyback auxiliary power supply 10 is segregated from the main power supply system, it requires a separate transformer 12, a separate transistor 14, and a separate pulse width modulator 15 which increases the cost and size of the power supply system.
Accordingly, what is needed is a circuit that decreases the cost and size of the power supply system. The circuit should be simple and adaptable to existing technology. The present invention addresses such a need.
A power supply system is disclosed. The system comprises a main power supply portion, the main power portion including a transformer, and an auxiliary power portion wherein the auxiliary power portion is coupled to the main power portion via the transformer.
Through the use of the power supply system in accordance with the present invention, the auxiliary output voltage is generated by the main power portion. Therefore, a circuit in accordance with the present invention provides the auxiliary output voltage by using the same pulse width modulator and switching devices used by the main power portion. The use of a power supply system in accordance with the present invention thereby eliminates the need for the components required to maintain the auxiliary output voltage. Accordingly, system space can be saved and there is also a reduction in manufacturing costs.